1. Field of the Invention
The present invention relates to a ceramic material and a fabrication method thereof, and in particular to a surface-treated ceramic material showing an increased strength and an oxidation-resistance and a fabrication method thereof.
2. Description of the Background Art
Aluminum nitride AlN has many attractive properties for electronic applications, such as high thermal conductivity, low thermal expansion coefficient, and high electrical resistivity. In addition, the AlN has low specific gravity, high-melting temperature, and high resistance to molten metals. A combination of these thermo-physical properties makes this ceramic for a strong candidate material for a variety of structural applications, such as parts for heat-engine, crucible materials for molten aluminum or gallium arsenide, and airborne ballistic armor materials.
The potentials of AlN, however, have not been fully utilized yet. One of the reasons limiting its wider applications is a low oxidation resistance of AlN at elevated temperatures. There have been many investigations on the oxidation behavior of AlN in various environments. In spite of some discrepancies in detail, it is generally agreed that the oxidation rate of AlN above 1000xc2x0 C. is so high in oxidizing atmospheres, such as in air, that a thick alumina layer is formed on the surface. Flaws generated on the alumina layer because of the thermal expansion mismatch between the alumina layer and the AlN substrate penetrate into the substrate, leading to a severe reduction in strength of the material. Therefore, for successful application at elevated temperatures, the oxidation resistance of this ceramic should be improved.
Accordingly, it is an object of the present invention to provide a surface-treated aluminum nitride and a fabrication method thereof which are capable of preventing oxidation behavior at an elevated temperature and of providing stable strength at an even elevated temperature.
It is another object of the present invention to provide a surface-treated aluminum nitride and a fabrication method thereof which are capable of surface-treating a lot of specimen at a time and conveniently.
To achieve the above objects, there is provided a surface-treated aluminum nitride including a silica layer formed on the aluminum nitride.
In another aspect, the present invention contemplates a method for fabricating a surface-treated aluminum nitride, comprising the step of depositing a silica by reacting a source of silicon with an atmosphere gas including oxygen or oxygen compound.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.